1911 Encyclopædia Britannica/Berberine
BERBERINE, C20H17NO4, an alkaloid occurring together with the alkaloids oxyacanthine C18H19NO3, berbamine C18H19NO3, hydrastine C21H21NO6, and canadine C20H21NO4, in Berberis vulgaris; it also occurs in other plants, Berberis aristata, B. aquifolium, Hydrastis canadensis, &c. It is a yellow, crystalline solid, insoluble in ether and chloroform, soluble in 4½ parts of water at 21°, and moderately soluble in alcohol. It is a monacid base; the hydrochloride, C20H17NO4·HCl, is insoluble in cold alcohol, ether and chloroform, and soluble in 500 parts of water; the acid sulphate, C20H17NO4·H2SO4 dissolves in about 100 parts of water. Canadine is a tetrahydroberberine.
Its constitution was worked out by W. H. Perkin (J.C.S., 1889, 55, p. 63; 1890, 57, p. 991). This followed from a study of the decomposition products, there being obtained hemipinic acid (CH3O)2C6H2(COOH)2, and a substance which proved to be ω-amino-ethyl-piperonyl carboxylic acid, CH2O2 : C6H2·COOH·CH2·CH2NH2. His formula was modified by Gadamer (Abs. J.C.S., 1902, 1, p. 555), who made the free base an aldehyde, but the salts of an iso-quinolinium type. This formula, which necessitates the presence of two asymmetric carbon atoms in an alkyl tetrahydroberberine, has been accepted by M. Freund and F. Mayer (Abs. J.C.S., 1907, 1, p. 632), who showed that two racemic propyl tetrahydroberberines are produced when propyl dihydroberberine is reduced.